# CVE-2026-83612

## Summary

- **CVE ID:** CVE-2026-83612
- **Severity:** HIGH
- **CVSS Score:** 8.7 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-178, CWE-400
- **Published:** Sep 1, 2026
- **Last Modified:** Sep 1, 2026

## Description

xmldom is a pure JavaScript W3C standard-based (XML DOM Level 2 Core) DOMParser and XMLSerializer module. From 0.9.0-beta.1 until 0.9.12, HTML-mode parsing through DOMParser.parseFromString() mishandles a mixed-case closing tag for the script, style, textarea, or title raw-text elements. parseHtmlSpecialContent, selected by isHTMLRawTextElement or isHTMLEscapableRawTextElement, uses a case-sensitive indexOf() and then calls substring() with a missing-close result of negative one, causing unstable parser progression and quadratic output amplification. A small untrusted text/html document can consequently consume disproportionate CPU and memory when parsed and serialized. This issue is fixed in @xmldom/xmldom version 0.9.12.

## Affected Products

- xmldom — xmldom (>= 0.9.0-beta.1, < 0.9.12)
- @xmldom — xmldom (>= 0.9.0-beta.1, < 0.9.12)

## References

- [CNA](https://github.com/xmldom/xmldom/security/advisories/GHSA-6mj3-qw4j-hgrw)
- [CNA](https://github.com/xmldom/xmldom/pull/1071)
- [CNA](https://github.com/xmldom/xmldom/commit/7ced40c06c28d151e996a97045018c3559ae4707)
- [CNA](https://github.com/xmldom/xmldom/releases/tag/0.9.12)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.30%
- **EPSS Percentile:** 22.4

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._